Gasoline composition



United States Patent O GASOLINE COMPOSITION Lawrence B. Scott,Lafayette, and Rupert C. Morris,

Berkeley, Calif., assignors to Shell Development Company, New York, N.Y., a corporation of Delaware No Drawing. Application November 14, 1955Serial No. 546,798

9 Claims. (Cl. 44--72) This invention relates to fuel compositions forinternal combustion engines, especially gasoline, containing a certainclass of organic boron compounds.

It is well known that certain combustion phenomena of spark-ignitioninternal combustion engines are advantageously affected by the presenceof boron in the combustion chamber of the engine. For example, it hasbeen found that gasoline containing minor amounts of boron in the formof soluble or dispersible boron compounds has an improved resistance tosurface ignition and a decreased tendency to raise the octanerequirement of the engine in which the gasoline is used. Among thecompounds previously proposed for such purposes are the trialkyl boratesand the trialkyl borines such as triisobutyl borate and triamyl borine,and more recently, certain classes of alkyl boronic acids and alkanediolesters thereof. Such compounds have been shown to be effective in theserespects but their use has been limited to a varying extent by therelatively high solubility of such compounds in water, and also by thelow resistance of such compounds to decomposition through hydrolysis.Such compounds are thus lost from gasoline, at least in part, by theleaching or hydrolyzing action of the free water with which the gasolineinvariably comes in contact during commercial storage and handling.Another disadvantage of such compounds is that the only ones known toresist hydrolysis and leaching to any material extent contain only smallamounts of boron in proportion to the rest of the molecule. Thusrelatively large concentrations of such compounds are necessary toachieve a desired concentration of boron in the gasoline.

It is, accordingly, a principal object of this invention to provide animproved hydrocarbon fuel composition for internal combustion engines. Amore particular object of the invention is to provide such a compositionwhich has improved combustion characteristics. A further object of theinvention is to provide a gasoline composition with improved resistanceto surface ignition and less tendency to increase the octane requirementof the engine in which it is used. Still another object of the inventionis to provide a boron-containing gasoline composition especiallyresistant to the action of water. Another object of the invention is toprovide a gasoline composition especially resistant to the action ofwater and containing a boron additive the boron content of which isespecially high. Another object of the invention is to provide aboron-containing gasoline composition the boron content of which can beespecially high. Other objects will be apparent from the description ofthe invention.

It has now been discovered that these objects and others are attained bythe addition to gasoline of a minor amount of certain heterocyclic boroncompounds. The boron gasoline additives of the present invention arehexa- 2,821,463 Ice Patented Jan. 28, 1958 2 tomic heterocyclic ringcompounds or mixtures thereof with normal boiling points no higher thanabout 500 C. The heterocyclic ring of these compounds contains threeboron atoms alternating with three nitrogen atoms. Each of the nitrogenatoms of the heterocyclic ring is attached directly to a carbon atom inan organic radical with a radical weight of at least 15, and each of theboron atoms of the heterocyclic ring is attached to a hydrogen atom, orto a carbon or nitrogen atom in a radical with a radical weight of atleast 15.

The boron compounds of the gasoline compositions of the invention thushave the general formula:

wherein X is a hydrogen, or'a radical with a radical weight of at least15 and attached to the boron atom directly through an atom of an elementhaving an atomic number of from 6m 7 inclusive; and wherein Y is aradical with a radical weight of at least 15 and attached to thenitrogen atom directly through a carbon atom.

It is preferred that X be an organic radical and that thering-connecting element of the X radical be carbon. It is also preferredthat both X and Y be organic radicals and contain no more than 10 carbonatoms, and especially organic radicals containing no atoms other thancarbon, hydrogen and nitrogen. Particularly suitable compounds are thosein which X and Y are hydrocarbyl groups containing no more than 5 carbonatoms, and especially no more than 3 carbon atoms. Still better,especially in the case of Y, are such hydrocarbyl groups in which theatom attached to the ring is a secondary or tertiary carbon atom.

Because of the limitation of the maximum boiling point of the boroncompound, and also so that the boron content of the compound bereasonably high, it is preferred that the total of the radical weightsof the ring substituents be no greater than 500. Particularlyadvantageous compounds are those which have an especially high boroncontent, such as those in which the total of the radical weight of thering substituents is no greater than 300, and preferably no greater than250. On the other hand, in order that the gasoline compositions of theinvention be especially resistant to the action of water, the total ofthe radical weights of the ring substituents of the heterocyclic boroncompound should be at least 48, and preferably at least 125.

The heterocyclic boron compounds of the compositions of the inventionare generally called borazoles, the name borazole indicating theunsubstituted hexatomic ring compound (BH-NH) and the substituents ofthe ring being named with N- and/ or 18- prefixes to designate theirpositions. Thus, for example, the compound with the structural formulaillustrated above, wherein each X is a methyl group and each Y is anisopropyl group, is called N-triisopropyl-B-trimethylborazole.

Among the borazoles suitable in the practice of the invention are:N-triphenyl-B-trimethylborazole,N-triphenyl-B-tris(dimethylamino)borazole,N-triphenyl-B-triethylborazole, N-tricyclohexyl-B-trimethylborazole, N-

\ triisopropyl-B-trimethylborazole, N-triisopropyl-B-triethylborazole,N-triethyl-B-trimethylborazole, N-triisopropyl- 3B-tris(dimethylamino)borazo1e, N-triisopropyl B triisopropylborazole,N-trimethyl-B-trimethylborazole, N-trimethyl-B-triaminoborazole, Ntriisopropyl-B-tris(monomethylamino)borazole,N,N"-diisopropyl-N'-methyl-B- trimethylborazole,N-triphenyl-B-triphenylborazole, N- tris 4-methylphenyl)-B-trimethylborazole, N-tribenZyl-B- tris (B-aminoethyl borazole,N-trimethyl-B-trianilinoborazole, N-triisopropyl-B-tripyrrylborazole,Netriisopropylborazole, N-trimethylborazole, N-triphenylborazole, N-tris tertiarybutyl) -B-tris (4-tolyl borazole, N -triisoproyl-B-tris-(isopropylamino)borazole, and the like.

The presence of lead or other metal-containing antidetonants in agasoline is well known to aggravate surface ignition and octanerequirement increase, although these problems arise to some extent evenwith the socalled clear fuels, which do not contain anti-detonants. Ithas been found that the presence of boron in a gasoline is effective indecreasing the severity of these problems whether or not the .gasolinealso contains an anti-detonant, although the advantage is greater if thegasoline does contain an anti-detonant, especially a tetraalkylleadautidetonant. Thus it is particularly advantageous to incorporate thepresent heterocyclic boron compounds into a gasoline containing ananti-detonant, especially a tetraalkyllead anti-detonant such astetraethyllead.

The following examples illustrate the boron additives of the presentinvention, their preparation and the benefits and advantages thereof.

EXAMPLE 1 Preparation of N-tris(2-pr0pyl)-B-trichloroborazoleN-tris(2-propyl)-B-trichloroborazole was prepared by reaction ofisopropylamine with boron trichloride in the presence of triethylaminesimilar to a procedure used by Jones and Kinney [1. Am. Chem. Soc. '61,1378 (1939)] for the preparation of N-triphenyl-B-trichloroborazole.This and other like compounds are especially suitable for thepreparation of the additives of the invention as in the followingexamples.

EXAMPLE 2 Preparation of N-tris(2-pr0pyt')-B-trimethylb0raz0le Areaction vessel was fitted with a ground glass stirrer, dropping funnel,condenser, and drying tube. Dry nitrogen was passed through the vesselfor approximately /2 hour, and 310 grams (1 mole) of N-tris(2-propyl)-B-trichloroborazole (prepared as in Example 1) in 500 ml. of ether wasadded. To this solution at room temperature wa added with stirring, overa period of 1 /2 hours, methylmagnesium chloride (3.2 moles) in 3 litersof ether.

The mixture was stirred for 15 hours, filtered to :remove the magnesiumchloride, and the filtrate was added slowly to 1 liter of saturatedammonium chloride solution at C., washed with water, and dried overanhydrous sodium sulfate. Evaporation of the ether followed bydistillation of the product gave 224 grams (90.9% of the theoreticalyield) of N-tris(2-propy1)-B- trimethylborazole, B. P. 101 C. (1 mm.Hg), M. P. 6870 C. The material analyzed 58.0% carbon and 12.1% hydrogenas compared to a theoretical carbon and hydrogen content of 57.8 and12.1%, respectively.

EXAMPLE 3 Preparation of N-tris(2-pr0pyl)-B-tris(dimethylamino) borazoleA reaction vessel was equipped with a ground glass stirrer, condenser,dropping funnel, and a drying tube. Dry nitrogen was passed through thevessel for approximately /2 hour, and 310 grams (1.0 mole) of N-tris (2-propyl)-B-trichloro-borazole in 2500 ml. of benzene was added. While thereaction mixture was kept .at 30 .C. with a water bath, a solution of180 grams (4.0'moles) .4 of anhydrous dimethylamine and 404 grams (4.0moles) of triethylamine in 1000 ml. of benzene was added over a periodof 2 hours. The reaction mixture was stirred at room temperature for 15hours, the triethylamine hydrochloride removed by suction filtration,and solvent was removed under reduced pressure on a hot water bath. Theproduct was distilled to give 278 grams (83% of the theoretical yield)of N-tris(2-propyl)-B-tris(dimethylamino)borazole, B. P. 128-132" C.(1.6 mm. Hg). The material analyzed 54.3%carbon and 12.1% hydrogen ascompared to a theoretical carbon and hydrogen content of 53.8 and 11.7%,respectively.

EXAMPLE 4 Preparation of N-tris(2-propyl) borazole A reaction vessel wasfitted with a stirrer, dropping funnel, condenser, and a drying tube.Dry nitrogen was allowed to flow through the vessel for V2 hour and then58 grams (1.5 moles) of sodium borohydride and 177 grams (3 moles) ofisopropylamine in 400 ml. of ether was added. To this mixture was added34 grams (0.5 mole) of boron trifiuoride etherate. After the reactionmixture had stirred for 15 hours, the ether was replaced with 500 ml. oftoulene, and the reaction mixture was refluxed for an additional 15hours. The precipitate was then removed by suction filtration, thesolvent removed under reduced pressure, and the product distilled in aClaisen still. The product, a colorless liquid, B. P. 46 C. (1.1 mm.Hg), weighed 27 grams. The material analyzed 15.3% boron as against atheoretical boron content of 15.7% for N-tris(2-propyl)borazole.

EXAMPLE 5 TABLE 1 Concentration,

percent w.

Compound Observation n-Butyl boronic anhydride (C4HOBO 3 0.82 Whiteprecipitate on standingovernight. Tr1s(dnnethylamm0)b0rmc 0. 50 Whiteprecipitate on standingfor 1 hour. N-Trimethyl-B-triethyl borazole 0. 66N 0 precipitate after 2 months. N-Trnsopropyl-B-trimcthyl b0raz0le 0. 35N 0 precipitate after l'wee N-Triphenyl-B-trimethyl borazole 0. 10 Do.be -Triphenyl-B-triethyl borazole 0. 12 D0 EXAMPLE 6 The followingresults also show the exceptional resistance to water of the gasolinecompositions of the invention. Isooctane solutions of each of thecompounds listed in Table 2 (at about 10% w. each) were shaken with anexcess of distilled water in one series of tests, and each of thesecompounds in the pure, undiluted state was shaken with an excess ofwater in another series of tests. In the latter case, when there was noimmediate change, the mixture was heated to about C. on a steam bath.

TABLE 2 Compound Isooctane Solution Compound Shaken Shaken With WaterWith Water Tricresyl borate Immediate white pre- Immediate whitecipitate. precipitate.

Triethyl borate do Immediate white precipitate plus evolution of heat.

N-tris(2-propy1)-B-tri- No change for at least N change at 90methylborazole. 16 hours. for at least 1 our.

N-tris(2-propyl)borazole do D0.

N-tris(2-propyl)-B-tri- Became cloudy im- Dissolvedimmedichloroborazole. mediately with evoately with evolulution of heat.tion of heat.

N -triphcnyl-B-triethyl- N 0 change for at least No change at 90borazole. 16 hours. 0. for at least 1 hour.

N-triphenyl-B-trido Do.

methyl-borazole.

N-triethyl-B-trimethyl- .do Do.

borazole.

N -tris (2-propyl) -B -tris- -do Slight precipitate(dimethylamino)boafter 16 hours at razole. 90 0 EXAMPLE 7 The benefitsof the gasoline compositions of the invention with respect to octanerequirement were shown in engine tests using a Lauson Model I-I-2engine. This engine is a single-cylinder, spark-ignition, Water-cooledengine with a 2% inch bore and a 2% inch stroke. It was modified forthese tests by increasing its compression ratio sufliciently to adjustthe clean-engine F-l octane number requirement (with primary referencefuel) to about 65. The engine was thoroughly cleaned at the beginning ofeach test on a particular fuel, and operated during the test with aspark advance of 25 BTDC and on a cylic schedule of 1 minute idling and3 minutes cruise. The lubricant used was a common commercial crankcaseoil. The octane requirement of the engine at full power output wasdetermined at least once a day during each test.

A base gasoline consisting of a blend of toluene, isooctane, and normalheptane containing sufficient motor mix fluid to supply 3.0 cc.tetraethyl lead per U. S. gallon was tested according to this procedure.The octane requirement of the engine leveled off after about 120 hoursat 6:1 octane numbers above the octant requirement of the clean engine.

To the same base gasoline was added 1.8 grams of N-tris(2-propyl)-B-trimethylborazole per gallon (0.20 gram boron per U. S. gallon). Whenthis fuel was tested according to the above procedure, the octanerequirement of the engine leveled off after about 180 hours at only 1 to2 octane numbers above the octane requirement of the clean engine.

EXAMPLE 8 The benetfis of the gasoline compositions of the invention insuppressing preignition or wild ping were shown in the engine testdesigned to measure deposit-induced ignition which is described byHirschler, McCullough, and Hall, Deposit Induced Ignition Evaluation inLaboratory Engine, a paper presented at the Symposium on Preignition,Society of Automotive Engineers, Atlantic City, June 7-12, 1953. Theengine used in this test is a CFR anti-knock test engine in which thestandard overhead valve cylinder is replaced by L-head cylinder. Theengine is operated on a cyclic schedule of 50 seconds of idling and 150seconds at full throttle. The engine is equipped with an ionization gapand a surface-ignition counter. It thus differentiates between normaland uncontrolled combustion and counts the number of incidences of thelatter.

By means of the above test, a commercial premium gasoline containing 3.0cc. TEL/U. S. gallon, and this same gasoline also containing 1.8 gramsper U. S. gallon of N-tris(2-propyl)-B-trimethylborazole per gallon(0.20 gram of boron per U. S. gallon) were compared for induction periodand corrosivity. In these tests the base gasoline was a 58.5 APIcommercial premium automotive gasoline containing suflicient motor mixfluid to supply 3.0 cc. tetraethyl lead per U. S. gallon, 0.0003% w. ofthe commercial oxidation inhibitor,N,N'-disecondarybutyl-p-phenylene-diamine, and 0.00003% w. of thecommercial metal deactivator, N,N-disalicylal-1,2-propane-diamine. I

This base gasoline has an induction period (average of two tests) of 9.9hours by ASTM method D-525. The induction period of the same basegasoline containing 3.6 grams of N-tn's(2-propyl)-B-trimethylborazoleper U. S. gallon (0.4 gram boron per U. S. gallon) was 11.0 hours. Theinduction period of the same base gasoline containing 4.0 grams ofN-tris(2-propyl)-B-tris(dimethylamino)borazole per U. S. gallon (0.4gram boron per U. S. gallon) was over 22 hours.

For the corrosivity tests, the base gasoline, the base gasolinecontaining 3.6 grams N-tris(2-propyl)-B-tn'- methylborazole per gallon,and the base gasoline containing 4.0 gramsN-tris(2-propyl)-B-tris(dimethylamino) borazole per gallon (compositionsindicated below as Base, Gasoline A, and Gasoline B, respectively) wereeach added to a separate phase of water and a sandblasted andisopentaneacetone washed drum steel strip was suspended into eachgasoline sample so as to extend through the interface and into the waterphase. The strips were observed and their appearance recordedperiodically as follows, each system being maintained at normal roomtemperature:

A gasoline containing from 0.005 to 1.0 gram of boron per U. S. gallon,in the form of N-tris(2-propyl)borazole, when tested according to theprocedures of Examples 5, 6, 7, and 8, shows remarkable benefits withrespect to resistance to the action of water, reduction of octanerequirement increase and suppression of surface ignition.

EXAMPLE 11 A gasoline containing from 0.005 to 1.0 gram of boron, per U.S. gallon, in the form of N-trimethyl-B-trimethylborazole, when testedaccording to the procedures of Examples 5, 6, 7, and 8, shows remarkablebenefits with respect to resistance to the action of water, reduction ofE octane requirement increase and suppression of surface ignition.

Since, as already mentioned, the boron content of the heterocyclic boroncompounds is very high, the effective concentrations of these compoundsin the gasoline compositions can be very small. Generally, it is onlynecessary to include in the gasoline composition an amount of compoundsufficient to supply a boron content of at least about 0.05 gram per U.S. gallon, and in many cases benefits are realized with as small anamount as 0.005 gram boron per U. S. gallon. On the other hand, it isdesirable that the concentration of compound should not be greater thansufficient to supply a boron content of about 1.0 gram per U. S. gallon,or preferably, about 0.5 gram per U. S. gallon. A preferredconcentration of compound is that suflicient to supply a boron contentof from about 0.2 to about 0.4 gram per U. S. gallon.

Besides the heterocyclic boron additive, the gasoline compositions ofthe invention can, and ordinarily will, contain other additives, such asthe common commercial additives, for example anti-detonants, such astetraethyl lead, iron carbonyl, dicyclopentadienyl iron and derivativesthereof, Xylidene and N-methylaniline, lead scavengers, such as ethylenedibromide and ethylene dichloride, dyes, spark plug antifoulants such astricresyl phosphate, dimethyl xylyl phosphate and diphenyl cresylphosphate and diphenyl cresyl phosphate, other deposit modifiers such asother boron compounds and lower alkyl phosphates and phosphites,oxidation inhibitors such as N,N- disecondary butyl P phenylenediamine,N n-butyl-paminophenol and 2,6 -ditertiarybutyl-4-methylphenol, metaldeactivators such as N,N'-disalicylal-1,2-propanediamine, rustinhibitors such as polymerized linoleic acids and N,C-disubstitutedimidazolines and the like.

We claim as our invention:

1. A gasoline composition consisting essentially of hydrocarbons boilingwithin the gasoline range and containing from about 0.005 to about 1.0gram of boron, per U. S. gallon, in the form of a borazole compoundboiling not higher than about 500 C. and having the formula:

wherein each X isselected from the group consisting of hydrogen and anorganic radical having a radical atomic weight of at least and attachedto a ring boron atom through an atom of an element having an atomicnumber of from 6 to 7 inclusive, and wherein each Y is an organicradical having a radical atomic weight of at least 15 and attached to aring nitrogen atom directly through a carbon atom.

2. A gasoline composition in accordance with claim 1,

8 wherein each Y is an organic radical containing from 1 to 10 carbonatoms.

3. A gasoline composition in accordance with claim 2, wherein each Y isa hydrocarbyl radical containing from 1 to 5 carbon atoms.

4. A gasoline composition in accordance with claim 3, wherein theborazole compound is N-tris (2-propyl) borazole.

5. A gasoline composition in accordance with claim 1, wherein the amountof boron present in the form of the borazole compound is from about 0.05to about 0.5 gram per U. S. gallon.

6. A gasoline composition consisting essentially of hydrocarbons boilingwithin the gasoline range and containing from about 0.005 to about 1.0gram of boron, per U. S. gallon, in the form of a borazole compoundboiling not higher than about 500 C. and having the formula:

wherein each X is an organic radical having a radical atomic weight ofat least 15 and attached to a ring boron atom through an atom of anelement having an atomic number from 6 to 7 inclusive, and wherein eachY is an organic radical having a radical atomic weight of at least 15and attached to a ring nitrogen atom directly through a carbon atom.

7. A gasoline composition in accordance with claim 6, wherein each X andeach Y is a hydrocarbyl radical containing from 1 to 5 carbon atoms.

8. A gasoline composition in accordance with claim 6, wherein theborazole compound is N-tris(2-propyl)-B- tris (dimethylamino borazole.

9. A gasoline composition in accordance with claim 7, wherein theborazole compound is N-tris(2-propyl)-B-trimethylborazole.

References Cited in the file of this patent UNITED STATES PATENTS2,720,448 Arimoto Oct. 11, 1955 2,720,449 Arimoto Oct. 11, 19552,741,548 Darling et a1 Apr. 10, 1956 FOREIGN PATENTS 722,537 GreatBritain Jan. 26, 1955 OTHER REFERENCES Recent Developments in theChemistry of the Boron Hydrides, by Schlesinger and Burg, ChemicalReviews, vol. 31, 1 942, recd in Patent Oflice September 10, 1942 pages27-31 (complete article, pages 141).

1. A GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF HYDROCARBONS BOILINGWITHIN THE GASOLINE RANGE AND CONTAINING FROM ABOUT 0.005 TO ABOUT 1.0GRAM OF BORON, PER U.S. GALLON, IN THE FORM OF A BORAZOLE COMPOUNDBOILING NOT HIGHER THAN ABOUT 500*C. AND HAVING THE FORMULA: